Press for extruding easily oxidising metal billets



Nov. 9, 1965 H. PISCHEL ETAL PRESS FOR EXTRUDING EASILY OXIDISING METAL BILLETS S Sheets-Sheet 1 Original Filed April 27, 1962 Nov. 9, 1965 H. PISCHEL ETAL 3,216,233

PRESS FOR EXTRUDING EASILY OXIDISING METAL BILLETS Original Filed April 27, 1962 5 Sheets-Sheet 14 I 20 j 7 E 4 s g y 21 Nov. 9, 1965 H. PISCHEL ETAL 3,216,233

PRESS FOR EXTRUDING EASILY OXIDISING METAL BILLETS Original Filed April 27, 1962 3 Sheets-Sheet 3 BEE 4e eeb United States Patent 3,216,233 PRESS FOR EXTRUDING EASILY OXIDISING METAL BHLLETS Hans Pischel, Stuttgart-Weilirndorf, and Franz-Josef Zilges, Rheydt, Germany, assignors to Schloemann Aktiengesellschaft, Dusseldorf, Germany Continuation of application Ser. No. 190,630, Apr. 27, 1962. This application Nov. 16, 1964, Ser. No. 412,884 Claims priority, application6Germany, May 4, 1961,

7 Claims. (Cl. 72270) This invention relates to a press for extruding easily oxidising metal billets in a protective gas atmosphere, and this application is a continuation of our co-pending application, Serial No. 190,630, filed April 27, 1962, now abandoned. The object of the invention is to permit the extruded material to be passed through the stages of heating, extrusion and cooling to the point of removal of the extruded pioduct from the press whilst in a protective gas atmosp ere.

Easily oxidising metal billets must not be exposed to the air, particularly when they are hot. However, it is difficult to arrange for such a billet to be transferred from a furnace in which a protective gas atmosphere is maintained into the billet container of a press without exposing it to the air.

The present invention overcomes this difliculty by dispensing with a heating furnace of conventional kind and by providing in direct association with the billet container an electrical heating device which precedes the billet container in axial alignment therewith, and at the same time designing the press in such a way that the stroke of the ram is of appropriate length and the punch suitably sized to push the billet out of the heating device into the billet container. In other words, it is proposed to heat the billet in a position in which it directly aligns with the billet container and to transfer the hot billet into the billet container by means of the punch of the press.

This form of construction permits a protective gas atmosphere to be maintained whilst these processes are carried out by the simple expedient of enclosing the space between the head of the press and the bedplate within a closed shell provided with means for admitting a protective gas into the space thus enclosed.

If it is desired to restrict the stroke of the ram to the length of the container plus that of the heating device, then provision must also be made for withdrawing or swinging the heating device, in a plane normal to the line of ram action, out of the way of the billet whilst this is being located in the container axis, and for then restoring the heating device into its former working position. However, a better solution is to make the stroke of the ram sufiiciently long to provide the necessary clearance for axial introduction of the billet into the heating device.

Since, particularly in horizontal presses, means are required for keeping the billet centralized with respect to the punch, it is further proposed to fit the heating device with an electrically non-conducting guide means for the billet. Such guide means may take the form of peripherally divided silicon plates which centre the billet inside the heating device.

Moreover, in order to prevent the billet from dropping through the heating device before it is heated it is proposed in vertical presses to suspend the billet inside the heating device from a-fiange or from projections.

This flange or the projections are suitably designed to shear oif when the billet is forcibly pushed into the billet container by the descending punch. In horizontal presses the provision of such retaining projections may be desirable for locating the billet in a predetermined position whilst it is being heated. If heating is by means of an induction coil, then the polarity of the current which flows through the coil is arranged to produce an axial magnetic force which in cooperation with the retaining projections will hold the billet in the desired position.

Since the extruded product emerges from the die at a high temperature steps must be taken to exclude air from contacting the hot product. According to the invention the die is directly connected in gas-tight manner with a protective tube which can be filled with a protective gas atmosphere, and which is withdrawable from the press together With the extrusion. This can be done by dividing the dieholder in one or more axial planes so that each division is withdrawable approximately at right angles to the line of extrusion. After withdrawal of the dieholder sections the die and the protective tube together with the stump and the extrusion can be axially removed from the press.

Preferably, the protective tube is a double walled tube provided with means, not shown, for impelling a current of protective gas into the annular space between the double walls, and thence through apertures in the inner wall into the central space of the tube, where it comes into contact with the extruded product. If this gas is sufiiciently cold it can be used to cool the extruded part to a temperature at which the protective tube can be removed without risk of the part being undesirably oxidised.

An embodiment of the invention in which the ram stroke is long enough to provide for axial introduction of the billet into the heating device will now be described in greater detail by reference to the accompanying drawings in which:

FIG. 1 is a general part sectional view of the more important parts of a press according to the invention,

FIG. 2 is the central portion of the press, in axial section on a larger scale, and,

FIG. 3 is the billet container as well as the heating device on a larger scale in a slightly modified press.

The bedplate 1 of the press supports a divided dieholder 2a, 2b. The left-hand half of the holder can be withdrawn to the left by a shift cylinder 3 and the right-hand half of the holder can be withdrawn to the right by a similar cylinder not shown in the drawing. The container 4 for the billet is supported by a holder 5, and can be axially slidably moved in conventional manner. The crosshead 6 of the press can be lifted by drawback rams 8 and forced downwards by the press ram working in the main cylinder 9. The main cylinder 9 is mounted on the head 10 of the press, the head being anchored to bedplate 1 by columns 11. v

The space between the press head ill) and bedplate 1 is completely enclosed by a possibly cylindrical shell 12, provided with closable openings, not shown, for blowing in a protective gas, as well as openings for the introduction by suitable loading gear, such as a manipulator, not shown, of a billet 13 into the position shown in the drawing. The protective gas is maintained at a slight gauge pressure to prevent air from entering the interior of the shell when the billet is being loaded into the press. From the illustrated position the billet can be pushed into a heating device 1 5 by the punch 14. The heating device comprises a casing 1 6 and a heating coil 17 and rests on an insulating plate 7. Located inside the heating coil are upright plates 18, for instance, silicon sheets which are peripherally divided, and which are not therefore excessively heated by the induction coil 17. The 'coil can be cooled by water admitted through a pipe 19 and leaving through a pipe 20.

In conventional manner the container 4 is provided with a liner 21 through which the container bears on the die 22. The latter is held in the divided die-holder 2a and 2b. The die is centrally located on the top of a jacketed protective tube '23. As indicated by arrow 24 a cool protective gas can be introduced through the jacket into the interior of the tube through openings -as at 25, to scavenge the tube, and to cool the. extruded product. 'When the two parts 2a and 2b of the dieholder have been withdrawn to opposite sides of the press the die 22 and the protective tube 23 can be lowered. The stump and the extrusion can then be cooled down completely outside the press whilst a fresh die and a fresh protective tube 24 are inserted in readiness for the next operation.

With reference more particularly to FIG. 3 it will be seen that the billet, consisting for instance of a core 26 of fissionable material, such as plutonium or uranium or the like, contained for instance in a zirconium shell 27, is enclosed for instance within a copper or aluminum sleeve 28 which has a solid upper end 28a with an annular flange or with welded or brazed projections 28b for suspending the billet from the edge of casing 116. Whereas the whole of portions 26 and 27 is forced through a the die by the punch, part 28a remains as the stump and finally fills the orifice of the die 22 so that no oxidizable or inflammable material remains in the die.

The manner of operation is roughly as follows: The punch '14 is retracted sufficiently to permit a billet 13 to be positioned as illustrated in FIGS. 1 and 2. The space inside shell 12 need not necessarily be filled exclusively with a protective gas. The billet 13 is then allowed to drop into the heating device '15 where it remains suspended by its upper flange 28b. The shell 12 is then sealed and the required gauge pressure built up by blowing in more protective gas. The heating device 16 is then switched on. As soon as the billet is hot enough it is pushed into the billet container 21 and extruded. At the end of the extruding operation only the copper or aluminum part 28a remains in the orifice of the die, the extrusion itself being contained inside the jacketed tube 23 protected from contact with air even through the die orifice. The jacketed tube 23 had been filled with protective gas before extrusion began, and during extrusion gas is flushed through the tube to keep it cool. When the extruding operation has been completed the parts 2a and 2b of the dieholder are retracted towards opposite sides and the protective tube 23 together with the die 22, the stump and the extrusion are lowered out of the press. At the lower end of the tube 23, not shown in the drawing, is an opening which can be opened and closed. It is opened for the introduction of pre-eooled protective gas through the protective tube 23 for cooling the extruded product until the same has reached a temperature which is low enough to permit contact with air without further risk.

What we claim is:

1. A method of extruding billets provided with lateral holding projections at the upper end, in a vertical. extrusion press provided with a hollow electrical heating device mounted on the container of the press, and an extrusion die, said method comprising the steps of retracting the press ram, inserting a billet to be extruded in the heating device with its lateral holding projections resting on and supported by the edge of the hollow therein, supplying electric current to the heating device for a long enough time to enable the heating device to heat the billet up to an appropriate temperature, and advancing the press ram so as to shear 01f the lateral holding projections from the billet and push the billet out of the heating device into the container, and then to extrude the billet through the die.

2. A method as defined in claim 1, in which the extrusion press is provided with a die holder comprising at least two parts movable toward and away from each other to hold or release the die, and a protective tube in gas-tight engagement with the die and extending therefrom in axial alignment, and the additional steps of moving the parts of said die holder together to hold the die in extruding position, pushing the heated billet through the die to extrude the same with the extruded product received within said protective tube and integral with the extrusion residue remaining in the die, moving the parts of said die holder apart to release the die, and removing the die, extrusion residue, extruded product and protective tube as a unit axially of the press.

'3. A method of extruding billets in an extrusion press having a ram, 2. die, a die holder comprising at least two parts movable toward and away from each other to hold or release the die, and a protective tube engaging the die and extending therefrom in axial alignment, said method comprising the steps of moving the parts of said die holder together to hold the die in extruding position, operating said ram to extrude a billet through said die with the extruded product received within said protective tube and integral with the extrusion residue remaining in the die, moving the parts of said die holder apart to release said die, and removing the die, extrusion residue, extruded product and protective tube as a unit from the press.

4. A method of extruding billets in an extrusion press having a ram, a billet receiving container, a hollow electrical heating device disposed in axial alignment between said container and said ram, a die, a die holder comprising at least two parts movable toward and away from each other to hold or release said die, and a protective tube engaging said die and extending therefrom in axial alignment, said method comprising the steps of retracting said ram away from said heating device a distance at least equal to the length of a billet to be extruded, moving the parts of said die holder together to hold said die in extruding position, inserting a billet in said heating device, applying an electric current to said heating device for a sufficient time to heat said billet to the desired extrusion temperature, advancing said ram to push said billet from said heating device into said container and thereafter through said die to extrude said billet with the extruded product received within said protective tube and integral with the extrusion residue remaining in said die, moving the parts of said die holder apart to release said die, and removing said die, extrusion residue, extruded product and protective tube as a unit from the press.

5. A method of extruding billets in an extrusion press having a ram, a billet receiving container, a hollow electrical heating device removably mounted on the container in axial alignment between the container and the ram, a die, a die holder comprising at least two parts movable toward and away from each other to hold or release said die, and a protective tube engaging said die and extending therefrom in axial alignment, said method comprising the steps of retracting said ram to clear said heating device, moving the parts of said die holder together to hold said die in extruding position, removing said heating device [from said container, inserting a billet in said heating device, replacing said heating device on said container, applying an electric current to said heating device for a sufi'icient time to heat said billet to the desired extrusion temperature, advancing said ram to push said billet from said heating device into said container and thereafter through said die to extrude said billet with the extruded product'received within said protective tube and integral with the extrusion residue remaining in said die, moving the parts of said die holder apart to release said die, and removing said die, extrusion residue, extrude-d product and protective tube as a unit from the press.

'6. An extrusion press including a ram, a die', a die holder comprising at least two parts movable toward and away from each other to hold the die in extruding position or release the same, a billetreceiving container disposed in axial alignment with said die and ram, and a protective tube connected to said die in gas-tight relationship and movable as a unit with said die, said tube extending from said die in axial alignment for receiving the extruded product, whereby upon completion of the extrusion operation and upon moving the parts of said die holder apart to release said die, said die, the extrusion residue in said die, the extruded product and said protective tube may be removed as a unit from said press.

7. An extrusion press as defined in claim 6, in which said protective tube comprises spaced outer and inner walls providing an annular space therebetween, the extruded product being received within the inner wall, and said inner wall having apertures therein communicating with said annular space, whereby a cooling gas may flow through said annular space and said aperture into the space Within said inner wall to contact and cool the extruded product.

References Cited by the Examiner UNITED STATES PATENTS Benjamin 207-16 Fredrickson 3-17186 Upton 207-10.3 Wischhusen et a1. 207-10.3 Wroughton et a1. 20710.11 Krause 207l7 Boccon-Gibod et al. 207-1011 Osborn et a1. 207-16 Ellis et a1. 207-1011 Kent 207-1.1

Haendeler 20716 CHARLES W. LANHAM, Primary Examiner. 

1. A METHOD OF EXTRUDING BILLETS PROVIDED WITH LATERAL HOLDING PROJECTIONS AT THE UPPER END, IN A VERTICAL EXTRUSION PRESS PROVIDED WITH A HOLLOW ELECTRICAL HEATING DEVICE MOUNTED ON THE CONTAINER OF THE PRESS, AND AN EXTRUSION DIE, SAID METHOD COMPRISING THE STEPS OF: RETRACTING THE PRESS RAM, INSERTING A BILLET TO BE EXTRUDED IN THE HEATING DEVICE WITH ITS LATERAL HOLDING PROJECTIONS RESTING ON AND SUPPORTED BY THE EDGE OF THE HOLLOW THEREIN, SUPPLYING ELECTRIC CURRENT TO THE HEATING DEVICE FOR A LONG ENOUGH TIME TO ENABLE THE HEATING DEVICE TO HEAT THE BILLET UP TO AN APPROPRIATE TEMPERATURE, AND ADVANCING THE PRESS RAM SO AS TO SHEAR OFF THE LATERAL HOLDING PROJEC- 